Mycoplasmas represent some of the smallest self-replicating microorganisms, and have unique properties among the prokaryotes. These properties include the need for cholesterol to maintain their membrane envelope, and the absence of an external wall. Mycoplasmas are known to cause pulmonary infection in humans, and it is widely known that mycoplasmas can cause disease in most animals including humans as well as animals of commercial importance such as cattle, swine, and fowl. (Razin et al., 1998, Microbiol. and Molecular Biology Review, 62(4):1094-1156; Maniloff et al. Eds., 1992, Mycoplasmas, Molecular Biology and Pathogenesis, American Society for Microbiology, Washington).
Frequent co-occurrence of mycoplasma with other microorganisms, such as chlamydia, has been observed in diseases involving cell proliferation (International Patent Application No. PCT/BR01/00083, filed Jul. 3, 2001 and BR PI 0002989-0, filed Jul. 3, 2001). This association appears to increase the virulence of both pathogens. Mycoplasmal lipoproteins are potent macrophage activators and have a comparable activity and distribution in mollicutes as the LPS of Gram-negative bacteria. (Razin et al. Eds., 2002, Molecular biology and pathogenicity of mycoplasmas, Kluwer Academic/Plenum Publishers, New York). Recently described toll-like receptors (TLR) in macrophages that are activated by products from pathogens such as mycoplasmal lipoproteins and LPS from bacteria have been demonstrated to be important for activation of the immune system and it appears that the efficacy of the immune response depends on which concomitant TLR s are activated. (Akira et al., 2001, Nature Immunol. 2:675-680).
Archaea are the most ancient microorganisms existing in nature, but have been characterized only recently. See, Woese et al., Proc Natl. Acad. Sci. U.S.A. 74: 5088-5090 (1977). They inhabit extreme environments and are constituted by lipid monolayer membranes. Rich alkaline atmosphere with sodium ions and metals prevents proliferation of other bacteria, but is favorable to archaea's growth. Archaea have been isolated from alkaline waters from the Dead Sea, the Great Salt Lake and Yellowstone National Park. They have a small size, can—just barely—be viewed with an optical microscope, and observation of structural details requires electron microscopy. See, Howland et al., The surprising archaea. Discovering another domain of life, Oxford University Press (New York, 2000). Some are considered hyperthermophilic as they survive in very high temperatures.
Another unusual characteristic of some archaea is that they appear to use metal as an energy source. See, Amend et al., F. E. M. S. Microbiol. Rev. 25: 175-243 (2001). It is considered that archaea usually need an anaerobic or nearly anaerobic environments to carry out oxidation-reduction reactions with participation of different chemical compounds, including metals.
Recently, a new kind of extremely small archaea, which is dependent on bigger archaea, was described and named nanoarchaea. See, Huber J et al., Nature 417: 63-67 (2002). With the exception of archaea that reside in the mammalian intestine and produce methane gases, there is no report of archaea existing within plants or animals. See, Florin T H J et al., Am. J. Gastroenterol. 95: 2872-2879 (2000).
Cutaneous lesions, for example, psoriasis and radiodermatitis resulting from radiotherapy, present obstacles to successful wound healing, as the lesions result from continued exposure to causative factors such as radiation therapy for cancer, or immune system dysfunction in psoriasis. In particular, the persistence of radiodermatitis lesions often requires the suspension of radiation therapy during cancer treatment in order to permit healing of the lesions. Such interruptions can be detrimental to the successful treatment of cancer.